The present invention relates to a rotary cutter for a mower for mowing grass or the like by a cord extending in a radial direction from a case and being rotated by a motor or the like via a shaft.
Conventionally, according to technology of this kind, there is constructed a system containing a cord on a reel, in which when a free end of the cord is worn out, methods of then reeling out the cord, includes stopping the engine, partially disassembling the rotating parts and loosening screws. Alternatively, there is fabricated a structure in which a plunger for moving the reel in an axial direction is provided at the front end of a shaft to which the cutter is attached and by pushing in the plunger while rotating, the reel and the housing are shifted with respect to each other to thereby reel out the cord as shown by Japanese Patent Laid-Open No. 5608/1982.
However, the conventional rotary cutters having the above-described constitutions pose the following problems: in the case of the former, the operation of reeling out the cord is extremely complicated, and in the case of the latter, the lever is struck to push it in while rotating, which is dangerous since the free end of the cord is thereby lowered and pebbles are scattered by the cord. Further, all parts are separated when disassembling the rotary cutter which is an extremely troublesome procedure, and scrupulous caution is required in reassembling them.
It is an object of the invention to provide a rotary cutter for a mower resolving the problems of the conventional technology, mentioned above, and which is capable of limiting operation of the reeling out of the cord in the case where the free end of the cord is worn out to only when the rotary cutter is rotating at low speed, so that pebbles or the like will not be scattered. A further object of the invention is to provide a rotary cutter for a mower capable of preventing all parts from being scattered when disengaging the rotary cutter and accordingly, facilitating reassembly.
In order to achieve the above-described objects, according to an aspect of the invention, there is provided a rotary cutter for a mower including a cord for mowing grass, upon rotation, a reel for taking in the cord and reeling out the cord intermittently, when the reel is rotated, a cover covering a case containing the reel, and a plunger projected downward from the case and movable in an axial direction with pressure for intermittently rotating the reel, wherein a ratchet held at a constant position by an urging means is moved outward to open against the direction of the urging means by centrifugal force which is produced by rotating the rotary cutter at a high speed and engaged with the plunger to thereby prevent the plunger from moving in an axial direction. The urging means comprises a return spring for pushing the plunger in an outward direction, and the reel and the plunger which are separate members are contained in the case and the cover which are connected to each other detachably. The reel is intermittently rotated by moving the plunger in an axial direction, and when the case and the cover are detached from each other, the case and the reel are separated from the plunger.
Further, according to another aspect of the invention, there is further provided an engaging means with a shaft fixed to a main body of the mower at a central portion of the cover for holding the plunger by the shaft.